1. Field of the Invention
The present invention relates to a Moving Picture Experts Group (MPEG) system, and in particular to an MPEG data receiving apparatus and an MPEG data transmitting/receiving method for updating scene description information of scene objects.
2. Description of the Related Art
In general, MPEG-4 is an object-oriented coding standard for multimedia. Since there are plural objects within a scene, temporal and spatial positions of the objects must be designated. The MPEG-4 standard, disclosed in October 1998 by the International Organization for Standardization/International Electrotechnical Commission (ISO/IEC), provides functions required for applications of the multimedia as the object-oriented coding standard.
MPEG-4 objects include video objects, audio objects and composite video and graphic objects. The objects may be edited within a scene.
An MPEG-4 scene configuration is composed of various objects and requires elements for synchronizing the objects. In addition, in order to construct and composite a scene and to display the scene on a user's terminal, descriptive information about the temporal and spatial positions and properties of the scene objects is necessary. The descriptive information is called scene description information.
The MPEG-4 standard adopts Binary Format for Scene Description (BIFS) as a format for providing the scene description information. The BIFS combines video and audio objects into a common binary format in order to reduce an amount of necessary information, and supports functions including designation of temporal and spatial positions of the objects or change of behavior of each object, and interaction with a user of the scene description information.
However, BIFS is limited and is not capable of treating or manipulating any object which is not defined in starting scene description information provided by a content provider.
A receiving apparatus of the prior art receives initial screen description information from the content provider. The initial screen description information includes information about the spatial and temporal positions and properties of nodes constituting a screen and information that is updated corresponding to occurring events, i.e., screen correction commands, such as, for example, a node insertion, a node deletion, or a node property (field) correction. For example, the initial screen description information includes information about whether a particular node is operable corresponding to an event, such as, for example, the node insertion, the node deletion, or the node property (field) correction occurring with respect to the particular node. Also, the initial screen description information includes the screen description information corresponding to predetermined events which may occur in the particular node.
According to the prior art, the content provider must transmit a large amount of the initial screen description information to the receiving apparatus; thus, transmission is inefficient in a network environment having a low bandwidth.